Facial onset sensory and motor neuronopathy (FOSMN) is a rare and slowly progressive motor neuron disorder. Affected people initially experience facial tingling and numbness which eventually spread to the scalp, neck, upper trunk and upper limbs. These sensory abnormalities are later followed by the onset of motor symptoms such as cramps, muscle twitches, difficulty swallowing, dysarthria, muscle weakness and atrophy. The hallmark of FOSMN is a reduced or absent corneal reflex (the reflex to blink when something touches the eye). The underlying cause is currently unknown. Most cases appear to occur sporadically in people with no family history of the condition. Although there is no consensus regarding the best treatment options for FOSMN, some affected people have temporary improvement in response to intravenous immunoglobulin or plasmapheresis.[1][2][3]

Signs and symptoms of facial onset sensory and motor neuronopathy (FOSMN) generally become apparent by age 54 (range 38-77 years) and vary significantly from person to person. The earliest symptoms include facial tingling and numbness which eventually spread to the scalp, neck, upper trunk and upper limbs. These sensory abnormalities often present months to years prior to the development of motor symptoms such as cramps, muscle twitches, difficulty swallowing, dysarthria, muscle weakness and atrophy. The hallmark of FOSMN is the reduced or absence of the corneal reflex (the reflex to blink when something touches the eye).[1][2][3]

Last updated: 11/23/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have
all the symptoms listed. This information comes from a database called the Human Phenotype Ontology
(HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO
is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

The underlying cause of facial onset sensory and motor neuronopathy (FOSMN) is currently unknown. Because the clinical features and severity of the condition can vary significantly from person to person, it is thought that there may be a multifactorial cause.[1] Some studies suggest that the condition may occur due to an abnormal immune response or neurodegeneration (degeneration of certain motor and sensory neurons, specifically).[1][2]

Studies have also shown that SOD1 and OPMDgenes may play a role in FOSMN; however, the specific association is unclear. Although there are currently no familial cases of FOSMN reported in the medical literature, some scientists suspect that newer genetic testing technologies may uncover additional genetic factors.[1]

There is currently no evidence to suggest that facial onset sensory and motor neuronopathy is inherited. To date, no familial cases have been reported which means that the condition appears to occur sporadically in people with no family history of the condition.[1]

Due to the small number of reported cases, there are no agreed upon diagnostic criteria for facial onset sensory and motor neuronopathy. A diagnosis is often suspected based on the presence of characteristic signs and symptoms. Additional tests may then be ordered to support the diagnosis and rule out other conditions that are associated with similar features. These include:[1]

Due to the rarity of the condition, the best approach for effective treatment is currently unclear. Several treatments have been mentioned in case reports including intravenous immunoglobulin (IVIG), plasmapheresis (PE), corticosteroids, azathioprine, mycophenolate mofetil, and rituximab. Although some patients showed temporary improvements with IVIG and PE, the majority of cases did not respond to any of these treatments.[1]

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.

Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

PubMed is a searchable database of medical literature and lists journal articles that discuss Facial onset sensory and motor neuronopathy. Click on the link to view a sample search on this topic.

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